The old and the new. At top, U.N. peacekeepers at a Swedish camp in the Sinai peninsula in 1957; at bottom, soldiers patrol the boundary between Eritrea and Ethiopia after two years of fighting in 2000.
A triumph of modern, or second-generation, U.N. peacekeeping: Members of the Sudan Peoples' Liberation Movement (SPLM) arrive at the rally in Juba in July 2011 as South Sudan prepares for its independence.
South Sudanese church and civil society leaders meet with the head of the U.N. Mission in the Republic of South Sudan (UNMISS) in July 2011
A close-up of stands with United Nations promotional items in Brobo, Côte d'Ivoire, during "UNOCI Days", a three-day sensitization and information campaign for a peaceful electoral environment held in June 2010.
Unrest and violence in spite of a peacekeeping presence: Following disputed November elections in Côte d'Ivoire, many were injured during marches in support of an opposition leader. Here they arrive at U.N. headquarters to receive medical treatment.
Frustrating efforts at peacekeeping in Somalia have prompted the United Nations to reassess its strategies in the post-Cold War era. Belgian and U.S. members of a peacekeeping contingent patrol Kismayo in April 1993.
Drought and famine have compounded violence in Somalia and devastated the population. Parents wait with their malnourished and dehydrated children in a corridor at a hospital in Mogadishu in August 2011.
The United Nations flag is lowered at a check post on the Gaza-Tel Aviv road as peacekeepers withdraw on May 19, 1967, after Egypt rescinded its invitation. A few days later, the Six Day War broke out.
Norwegian troops with the U.N. peacekeeping mission in the former Yugoslavia make their way up “Sniper Alley” in Sarajevo in November 1995.
In 1992, a Canadian UNPROFOR soldier visits with two young Croatian boys, one of whom holds a toy gun.
This body exhumed at Srebrenica in 2000 appears to be a victim blindfolded and bound before he was killed.
These postage stamps issued by the United Nations reflect its long-term commitment to peacekeeping.
The iconic blue helmet worn by United Nations peacekeeping personnel in front of a U.N. flag.
Hervé Ladsous was recently appointed the new head of United Nations peacekeeping.
Women stand by a monument to victims of the 1995 Srebrenica massacre during a memorial ceremony in Potocari, Bosnia and Herzegovina, in July 2007.
An aircraft rusts at Cyprus' Nicosia International Airport, abandoned in 1974 when fighting erupted between Greek and Turkish Cypriots. A U.N. peacekeeping force has been deployed there since 1964.
Australian peacekeepers patrol in East Timor in 2002.
Canadian and Panamanian peacekeepers inspect a radio while stationed in the Sinai in 1974.
Zambian members of the U.N. Mission in Sudan (UNMIS) patrol in an armored personnel carrier in May 2011. The successful liberation of South Sudan is a triumph of second-generation peacekeeping.
Lester B. Pearson, a Canadian civil servant who won the Nobel Peace Prize in 1957 for organizing UNEF in response to the Suez Canal crisis.
German soldiers in an armored personnel carrier observe the dedication of a well they helped dig in Somalia in 1993 as part of peacekeeping efforts there.